1. Field of the Invention
The present invention relates to a resonator, and a piezoelectric resonance device, and.
2. Description of the Related Art
A resonator, an example of a piezoelectric resonance device, is used in various types of electronic equipment as a circuit for generating clock signals etc. In general, a resonator is provided with a piezoelectric element and a capacitor. These are made to constitute a signal, generating circuit by connection of the input-output lead terminals and the ground lead terminals. The piezoelectric element and capacitor are integrally covered by a sealing resin comprised of an epoxy resin etc.
It is generally known to use an input-output lead terminal for such a resonator. For example, such a lead terminal is disclosed in Japanese unexamined utility Model Publication (Kokai) No. 63-131414. The lead terminal shown in this publication is produced by punching a metal sheet to form a strip which is then cut and bent.
In the lead terminal shown in this publication, there is the problem of a large number of steps required for production. Furthermore, since this lead terminal is structured to hold an end of the piezoelectric element from the two different sides, the area of the vibrating section of the piezoelectric element is reduced and the longitudinal width of the piezoelectric element has to be increased by the amount of the area required for holding the ends. This runs counter to the demands for reducing the size of piezoelectric resonators.
As another lead terminal according to the related art, there is known the lead terminal shown in Japanese Unexamined Patent Publication (Kokai) No. 3-421. The lead terminal shown in this publication is produced by punching a metal sheet to form a T-shape and then bending the ends to form a U-shape.
However, the lead terminal shown in the 3-421 publication requires a large number of steps for production. Additionally, the lead terminal disclosed in the 3-421 publication is structured to hold a piezoelectric element from two sides. Therefore, the area of the vibrating section of the piezoelectric element is reduced. Thus, the longitudinal width of the piezoelectric element must be increased by the amount of the area required for holding the ends of the piezoelectric element. Furthermore, this solution does not allow the size of the piezoelectric resonators to be reduced.
Further, as shown in Japanese Unexamined Patent Publication (Kokai) No. 63-131414, the resonator of the related art had the piezoelectric element and capacitor positioned facing each other substantially in parallel. If such a piezoelectric resonator is used in an environment with severe temperature changes (for example, mounted in an automobile), however, there is the problem of a susceptibility to reduce vibration. To prevent this problem, it has been confirmed that the piezoelectric element and the capacitor can be positioned offset from each other in the vertical direction. The piezoelectric element and the capacitor are then connected and secured by the lead terminals. Once again, this solution does not allow the size of the piezoelectric resonators to be reduced.
Further, in the resonator of the related art, the size of the vibrating space formed in the sealing resin surrounding the area around the piezoelectric element was determined without regard to the frequency band of the piezoelectric element and therefore there was the problem that good resonance characteristics could not be obtained.